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Number System

Fast trick to solve number system

Q .If the difference between the reciprocal of a positive proper fractionand the fraction itself be 21/14, the fraction is-

Let number be the x -

(1/x ) - ( x/1 ) = 21/14

(1 - x2 )/x = 21/14

14 (1 - x2 ) = 21x

14x2 + 21x - 14 = 0

solve the equation with fast trick method as disccused another video-

so x=1/2 or x=-2/1

So the fraction is 1/2.